Spectacular ‘Sideways Glance’ of Mt. Sharp in Gale Crater

by Nancy Atkinson on August 17, 2012

Yep, you really want to click on this link to see the full color version of this great oblique view of Mt. Sharp (a.k.a. Aeolis Mons) in Gale Crater, taken by the HiRISE camera on the Mars Reconnaissance Orbiter. Or you can click here to see the full “raw” strip from the spacecraft.

“The viewing angle is 45 degrees, like looking out an airplane window,” wrote HiRISE Principal Investigator Alfred McEwen on the HiRISE website. McEwen noted that this color version doesn’t show the Curiosity rover or the hardware left over from the landing on Mars, but it does provide a great view of Gale Crater’s central mound.

So how “true” is the color in this image?

“It may be close, but not true,” Christian Schaller from the HiRISE team told Universe Today. Schaller pointed out the description (pdf) of color in HiRISE images from the HiRISE team:

It isn’t natural color, as seen by normal human eyes, because the IR, RED, and BG channels are displayed in red, green, and blue colors. For the Extras products, each color band is individually stretched to maximize contrast, so the colors are enhanced differently for each image based on the color and brightness of each scene. Scenes with dark shadows and bright sunlit slopes or with both bright and dark materials are stretched less, so the colors are less enhanced than is the case over bland scenes.

Jim Bell, the lead scientist for the Pancam color imaging system on the Mars Exploration Rovers, said he likes to use the term “approximate true color” because the MER panoramic camera images are estimates of what humans would see if they were on Mars. Other colleagues, Bell said, use “natural color.”

“We actually try to avoid the term ‘true color’ because nobody really knows precisely what the ‘truth’ is on Mars,” Bell told Universe Today in 2007 for an article about the art of extraterrestrial photography. In fact, Bell pointed out, on Mars, as well as Earth, color changes all the time: whether it’s cloudy or clear, the Sun is high or low, or if there are variations in how much dust is in the atmosphere. “Colors change from moment to moment. It’s a dynamic thing. We try not to draw the line that hard by saying ‘this is the truth!’”

For more great shots from HiRISE, check out their website.

Source: HiRISE


Nancy Atkinson is Universe Today's Senior Editor. She also works with Astronomy Cast, and is a NASA/JPL Solar System Ambassador.

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